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Abstract:

The present invention includes an apparatus and method for removing oil
from a oil-containing liquid comprising oil and gas comprising: a source
of oil-containing liquid; and a membrane contactor system in fluid
communication with the source of oil-containing liquid, the membrane
contactor system comprising one or more membrane contactors having a
first and a second surface, wherein the first surface coalesces oil and
removes gas from the oil-containing liquid, and the oil and gas are
collected on the second surface from the oil-containing liquid.

Claims:

1. An apparatus for removing oil from an oil-containing liquid comprising
oil and gas comprising: a source of oil-containing liquid; and a membrane
contactor system in fluid communication with the source of oil-containing
liquid, the membrane contactor system comprising one or more membrane
contactors having a first and a second surface, wherein the first surface
coalesces oil and removes gas from the oil-containing liquid, and the oil
and gas are collected on the second surface from the oil-containing
liquid.

2. The apparatus of claim 1, further comprising a solid removal system
for removing small, medium and large solids from an oil/water mixture to
form an oil and water stream containing only solids smaller than 30
microns, wherein the small, medium or large solids are removed with at
least one of a sand filter, a rock filter, a porous ceramic material, a
centrifuge, a mesh, a particulate filter, a sieve, a strainer, or
gravity.

4. The apparatus of claim 1, wherein the oil-containing liquid is at
least one of: not subjected to gravity separation prior to processing,
subjected to gravity separation prior to processing, or subjected to
centrifugation prior to processing.

5. The apparatus of claim 1, wherein the membrane contactor is
pre-treated with a soak that is defined further as comprising a
hydrophobic liquid soak or hydrophobic liquid circulation in the membrane
contactor with the hydrophobic liquid on at least one of the first, the
second, or both the first and second surfaces of the membrane contactor.

6. The apparatus of claim 1, wherein the membrane contactor is
pre-treated with a soak that is defined further as comprising contacting
at least one of the first, the second, or both the first and second
surfaces of the membrane contactor with an alcohol, followed by a
caustic, followed by an acid, followed by drying with an inert gas,
followed by an hydrophobic liquid soak or hydrophobic liquid circulation
in the membrane contactor.

7. The apparatus of claim 1, wherein the oil-containing liquid is
processed by the system within 1, 2, 4, 6, 8, 12, 24, 26, 48 or 72 hours
from removal of large solids.

8. The apparatus of claim 1, wherein the membrane contactor is a
hydrophobic membrane or membrane module that comprises hollow fiber
microporous membranes.

10. The apparatus of claim 1, wherein the oil separated from the
oil-containing liquid by the membrane contactor is coalesced with a
counterflowing fluid, wherein the at least one counterflowing fluid
selected from hydrophobic liquid, non-polar fluid, alkanes such as
hexane, aromatic fluid such as benzene, toluene, ethers such as diethyl
ether, halogenated fluid such as chloroform, dichloromethane, and esters
such as ethyl acetate.

11. The apparatus of claim 1, further comprising a membrane cleaning
system that removes debris that clogs the membrane contactor system, and
optionally comprising a clog detector that detects a clog at the membrane
contactor system.

12. The apparatus of claim 1, further comprising an oil and gas separator
in fluid communication with second surface of the membrane contactor.
This claim serves to say that an oil and gas separator can be downstream.

13. The apparatus of claim 1, wherein the apparatus operates at less than
100 psi.

16. The apparatus of claim 1, wherein the oil and gas are separated from
the oil-containing liquid in a single step.

17. The apparatus of claim 1, wherein a collection fluid is in contact
with the second surface of the membrane contactor.

18. A method for isolating oil from an oil-containing liquid comprising
the steps of: obtaining an oil-containing liquid that comprises oil and
one or more gases; contacting the oil-containing liquid onto a first
surface of one or more membrane contactors to coalesce the oil on the
first surface and remove the gas; and collecting the coalesced oil and
removed gas from the second surface of the membrane contactor.

19. The method of claim 18, further comprising a solid removal system for
removing small, medium and large solids from an oil/water mixture to form
an oil and water stream containing only solids smaller than 30 microns,
wherein the small, medium or large solids are removed with at least one
of a sand filter, a rock filter, a porous ceramic material, a centrifuge,
a mesh, a particulate filter, a sieve, a strainer, or gravity.

21. The method of claim 18, wherein the oil-containing liquid is at least
one of: not subjected to gravity separation prior to processing,
subjected to gravity separation prior to processing, or subjected to
centrifugation prior to processing.

22. The method of claim 18, wherein the oil-containing liquid is
processed by the system within 1, 2, 4, 6, 8, 12, 24, 26, 48 or 72 hours
from removal of large solids.

25. The method of claim 18, wherein the oil separated from the
oil-containing liquid by the membrane contactor is coalesced with a
counterflowing fluid, wherein the at least one counterflowing fluid
selected from hydrophobic liquid, non-polar fluid, alkanes such as
hexane, aromatic fluid such as benzene, toluene, ethers such as diethyl
ether, halogenated fluid such as chloroform, dichloromethane, and esters
such as ethyl acetate.

26. The method of claim 18, further comprising a membrane cleaning system
that removes debris that clogs the membrane contactor system, and
optionally comprising a clog detector that detects a clog at the membrane
contactor system.

27. The method of claim 18, further comprising the step of separating the
oil from the gas and collecting the gas for further use.

28. The method of claim 18, further comprising the step of separating the
oil from the gas by exposing the coalesced oil to reduced pressure, in a
vessel, tank or membrane.

29. The method of claim 18, wherein the gas removed is selected from at
least one of O2, CO2, H2S, methane, ethane, propane,
butane, pentane, or hexane.

30. The method of claim 18, wherein the oil and gas are separated from
the oil-containing liquid in a single step.

31. The method of claim 18, further comprising the step of flowing a
collection fluid on the second surface of the membrane contactor.

32. The method of claim 18, further comprising the step of monitoring a
change in the pH, ionic strength, oxidative state, electrical resistance,
charge, or contamination of the oil-containing liquid to determine the
removal of gas and oil from the oil-containing liquid.

34. The method of claim 18, further comprising the step of determining
the step of monitoring a change in the pH, ionic strength, oxidative
state, electrical resistance, charge, or contamination of the
oil-containing liquid and depending on the change adding one or more
ions, antibiotics, oxidizers, reducers, surfactants, detergents,
chelators, hydrophilic liquids, hydrophobic liquid, acids, or bases.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and is a continuation-in-part
of U.S. patent application Ser. No. 14/052,516, filed Oct. 11, 2013,
which claims priority to U.S. Provisional Patent Application Ser. No.
61/659,918, filed Jun. 14, 2012 and U.S. Ser. No. 61/769,286, filed Feb.
26, 2013. This application is also a continuation-in-part and claims
priority to U.S. patent application Ser. No. 13/918,766, filed Jun. 14,
2013; which is a continuation-in-part and claims priority to U.S. Ser.
No. 13/358,897, filed Jan. 26, 2012 which is a continuation-in-part and
claims priority to U.S. Ser. No. 13/280,028, filed Oct. 24, 2011 which is
a continuation-in-part and claims priority to U.S. Ser. No. 13/006,342,
filed Jan. 13, 2011 which claims priority to U.S. Provisional Application
Ser. No. 61/295,607, filed Jan. 15, 2010, the entire contents of all of
which are incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

[0002] The present invention relates in general to the field of insoluble
oil recovery from liquid sources, and more particularly, to a microporous
membrane based method for recovering oil and gas.

STATEMENT OF FEDERALLY FUNDED RESEARCH

[0003] None.

BACKGROUND OF THE INVENTION

[0004] Without limiting the scope of the invention, its background is
described in connection with recovery methods for insoluble and low
solubility compounds having economic value from aqueous mixtures that may
include one or more types of biological cells or cellular debris.

[0005] U.S. Pat. No. 3,956,112, issued to Lee, et al., is directed to a
membrane solvent extraction. Briefly, this patent is said to describe a
membrane solvent extraction system that is used to separate two
substantially immiscible liquids and extract a solute through a solvent
swollen membrane from one solvent liquid phase to the extracting solvent
liquid without direct contact between the liquid phases. The membrane
extraction method has advantages over conventional solvent extraction and
may be applied as the mechanism in separation, purification, pollutant
removal and recovery processes. This reference relies on liquid
extraction, as the solvent swells the membrane to provide the separation.

[0006] U.S. Pat. No. 4,439,629 issued to Ruegg (1984) describes a process
for extracting either or both beta-carotene or glycerine from algae
containing these substances, especially from algae of the genera
Dunaliella. According to the Ruegg patent either or both of beta-carotene
or glycerine can be extracted from algae. If it is desired to extract
beta-carotene, the algae are first treated with calcium hydroxide and
then filtered. The residue from this filtration is treated with a
beta-carotene solvent, which removes the beta-carotene from the residue
and into the solvent. The beta-carotene can be recovered from the solvent
by conventional means. If it is desired to extract glycerine, the
filtrate from the treatment of the algae with calcium hydroxide is
neutralized, concentrated and the residue from the solid is treated with
a lower alkanol to remove glycerine from the residue.

[0007] U.S. Pat. No. 5,252,220, issued to Coughlin, et al., is directed to
the preparation of analytical samples by liquid-liquid extraction using
microporous hollow-fiber membranes. Briefly, this patent is said to teach
a method and apparatus for accomplishing improved liquid-liquid
extraction employing microporous hollow-fiber membranes. A number of
possible modes of liquid-liquid extraction are possible according to the
invention. As with the prior art, this patent relies on the interaction
between two liquids, one on the contact side and one on the other side of
the membrane for separation.

[0008] U.S. Pat. No. 5,378,639 issued to Rose et al. (1995) discloses a
method for the solvent-extraction of β-carotene from an aqueous
algal biomass suspension, whereby a vegetable oil which is immiscible
with water is mixed with an aqueous biomass suspension, the biomass
containing the β-carotene, to form a mixture of the organic phase
and the aqueous suspension, whereby the β-carotene is caused to
dissolve in the organic phase. This is followed by separation of the
organic phase from the aqueous phase by passing the organic phase
containing the dissolved β-carotene through a semi-permeable
membrane to effect microfiltration or ultrafiltration of the organic
phase. The membrane is of a material that is hydrophobic and the organic
phase is passed through the membrane with a pressure drop across the
membrane which is lower than that which causes the aqueous phase to pass
through the membrane.

[0009] U.S. Pat. No. 5,938,922 issued to Fulk, Jr., et al., is directed to
a contactor for degassing liquids. Briefly, these inventors teach a
contactor for degassing liquids includes a perforated core, a plurality
of microporous hollow fibers, and a shell, wherein the fibers surround
the core and have two ends. The system for degassing liquids includes a
source of liquid containing a gas, a source of vacuum, and the contactor.

[0010] U.S. Pat. No. 6,436,290, issued to Glassford is directed to a
method and apparatus for separating mixtures of organic and aqueous
liquid phases. Briefly, this patent is said to include a method and
apparatus for separating a mixture containing an aqueous liquid and an
immiscible organic phase using microporous hollow fibers. Such mixtures
are separated into a substantially organic-free aqueous phase and a
substantially aqueous-free organic phase. The mixture is pressurized in a
controlled low shear manner to minimize emulsification as it is contacted
with the fibers. Productivity is said to be enhanced by separating as a
third product stream, a further organic phase containing only small
amounts of an aqueous phase, which for some applications can usefully be
combined with the substantially aqueous-free organic phase.

[0011] In contrast to the vacuum used in U.S. Pat. No. 5,938,922, U.S.
Pat. No. 8,506,685, issued to Taylor, et al., is directed to a
high-pressure liquid degassing membrane contactors and methods of
manufacturing and use. Briefly, this patent teaches an improved liquid
degassing membrane contactor or module in a high-pressure housing and at
least one degassing cartridge therein. The high pressure housing is a
standard, ASME certified, reverse osmosis (RO) or water purification
pressure housing or vessel (made of, for example, polypropylene,
polycarbonate, stainless steel, corrosion resistant filament wound
fiberglass reinforced epoxy tubing, with pressure ratings of, for
example, 150, 250, 300, 400, or 600 psi, and with, for example 4 or 6
ports, and an end cap at each end) and that the degassing cartridge is a
self-contained, hollow-fiber membrane cartridge adapted to fit in the RO
high pressure housing.

SUMMARY OF THE INVENTION

[0012] The present invention describes additional methods for coalescing
insoluble oil from mixtures using a hydrophobic microporous hollow fiber
membrane. In one embodiment, the present invention is an apparatus for
removing oil from an oil-containing liquid comprising oil and gas
comprising: a source of oil-containing liquid; and a membrane contactor
system in fluid communication with the source of oil-containing liquid,
the membrane contactor system comprising one or more membrane contactors
having a first and a second surface, wherein the first surface coalesces
oil and removes gas from the oil-containing liquid, and the oil and gas
are collected on the second surface from the oil-containing liquid. In
one aspect, the apparatus further comprises a solid removal system for
removing small, medium and large solids from an oil/water mixture to form
an oil and water stream containing only solids smaller than 30 microns,
wherein the small, medium or large solids are removed with at least one
of a sand filter, a rock filter, a porous ceramic material, a centrifuge,
a mesh, a particulate filter, a sieve, a strainer, or gravity. In another
aspect, the oil-containing liquid is at least one of an oil-rich stream,
crude oil, transportation fuel, heating oil, refined petroleum products,
petrochemicals, bio-oils, renewable oils, vegetable oils, reclaimed oils,
waste oils, oil industry liquid streams, oil contaminated water or brine,
drilling mud, produced water and oil sands tailings. In another aspect,
the oil-containing liquid is at least one of: not subjected to gravity
separation prior to processing, subjected to gravity separation prior to
processing, or subjected to centrifugation prior to processing. In
another aspect, the membrane contactor is pre-treated with a soak that is
defined further as comprising a hydrophobic liquid soak or hydrophobic
liquid circulation in the membrane contactor with the hydrophobic liquid
on at least one of the first, the second, or both the first and second
surfaces of the membrane contactor. In another aspect, the membrane
contactor is pre-treated with a soak that is defined further as
comprising contacting at least one of the first, the second, or both the
first and second surfaces of the membrane contactor with an alcohol,
followed by a caustic, followed by an acid, followed by drying with an
inert gas, followed by an hydrophobic liquid soak or hydrophobic liquid
circulation in the membrane contactor. In another aspect, the
oil-containing liquid is processed by the system within 1, 2, 4, 6, 8,
12, 24, 26, 48 or 72 hours from removal of large solids. In another
aspect, the membrane contactor is a hydrophobic membrane or membrane
module that comprises hollow fiber microporous membranes. In another
aspect, the membrane contactor is a hydrophobic hollow fiber membrane
comprises polyethylene, polypropylene, polyolefins, polyvinyl chloride
(PVC), amorphous polyethylene terephthalate (PET), polyolefin copolymers,
poly(etheretherketone) type polymers, surface modified polymers, mixtures
or combinations thereof or a surface modified polymer that comprises
polymers modified chemically at one or more halogen groups by corona
discharge or by ion embedding techniques. In another aspect, the oil
separated from the oil-containing liquid by the membrane contactor is
coalesced with a counterflowing fluid, wherein the at least one
counterflowing fluid selected from hydrophobic liquid, non-polar fluid,
alkanes such as hexane, aromatic fluid such as benzene, toluene, ethers
such as diethyl ether, halogenated fluid such as chloroform,
dichloromethane, and esters such as ethyl acetate. In another aspect, the
apparatus further comprises a membrane cleaning system that removes
debris that clogs the membrane contactor system, and optionally
comprising a clog detector that detects a clog at the membrane contactor
system. In another aspect, the apparatus further comprises an oil and gas
separator in fluid communication with second surface of the membrane
contactor. This claim serves to say that an oil and gas separator can be
downstream. In another aspect, the apparatus operates at less than 100
psi. In another aspect, the apparatus operates at 5, 10, 20, 30, 40, 50,
60, 70, 80, 90, 95, 5 to 95, 10 to 90, 20 to 80, 30 to 70, 40 to 50, 5 to
15, 10 to 30, 20 to 40, 40 to 60, 50 to 70, 60 to 80, 80 to 90, or 90 to
95 psi. In another aspect, the gas removed is selected from at least one
of O2, CO2, H2S, N2, CO, saturated or unsaturated
light hydrocarbons, methane, ethane, propane, butane, pentane, ethylene,
propylene, or hexane. In another aspect, the oil and gas are separated
from the oil-containing liquid in a single step. In another aspect, a
collection fluid is in contact with the second surface of the membrane
contactor. In another aspect, a vacuum is in contact with the second
surface of the membrane.

[0013] Another embodiment of the present invention includes a method for
isolating oil from an oil-containing liquid comprising the steps of:
obtaining an oil-containing liquid that comprises oil and one or more
gases; contacting the oil-containing liquid onto a first surface of one
or more membrane contactors to coalesce the oil and gas on the first
surface; and collecting the coalesced oil and gas from the oil-containing
liquid on the second surface of the membrane contactor. In one aspect,
the method further comprises a solid removal system for removing small,
medium and large solids from an oil/water mixture to form an oil and
water stream containing only solids smaller than 30 microns, wherein the
small, medium or large solids are removed with at least one of a sand
filter, a rock filter, a porous ceramic material, a centrifuge, a mesh, a
particulate filter, a sieve, a strainer, or gravity. In another aspect,
the oil-containing liquid is at least one of an oil-rich stream, crude
oil, transportation fuel, heating oil, refined petroleum products,
petrochemicals, bio-oils, fermentation broth, growth media, renewable
oils, vegetable oils, reclaimed oils, waste oils, oil industry liquid
streams, oil contaminated water or brine, drilling mud, produced water
and oil sands tailings. In another aspect, the oil-containing liquid is
at least one of: not subjected to gravity separation prior to processing,
subjected to gravity separation prior to processing, or subjected to
centrifugation prior to processing. In another aspect, the oil-containing
liquid is processed by the system within 1, 2, 4, 6, 8, 12, 24, 26, 48 or
72 hours from removal of large solids. In another aspect, the membrane
contactor is a hydrophobic membrane or membrane module comprises hollow
fiber microporous membranes. In another aspect, the membrane contactor is
a hydrophobic hollow fiber membrane comprises polyethylene,
polypropylene, polyolefins, polyvinyl chloride (PVC), amorphous
polyethylene terephthalate (PET), polyolefin copolymers,
poly(etheretherketone) type polymers, surface modified polymers, mixtures
or combinations thereof or a surface modified polymer that comprises
polymers modified chemically at one or more halogen groups by corona
discharge or by ion embedding techniques. In another aspect, the oil
separated from the oil-containing liquid by the membrane contactor is
coalesced with a counterflowing fluid, wherein the at least one
counterflowing fluid selected from hydrophobic liquid, non-polar fluid,
alkanes such as hexane, aromatic fluid such as benzene, toluene, ethers
such as diethyl ether, halogenated fluid such as chloroform,
dichloromethane, and esters such as ethyl acetate. In another aspect, the
method further comprises a membrane cleaning system that removes debris
that clogs the membrane contactor system, and optionally comprising a
clog detector that detects a clog at the membrane contactor system. In
another aspect, the method further comprises the step of separating the
oil from the gas and collecting the gas for further use. In another
aspect, the method further comprises the step of separating the oil from
the gas by exposing the coalesced oil to reduced pressure, in a vessel,
tank or membrane. In another aspect, the gas removed is selected from at
least one of O2, CO2, H2S, methane, ethane, propane, butane, pentane, or
hexane. In another aspect, the oil and gas are separated from the
oil-containing liquid in a single step. In another aspect, the method
further comprises the step of flowing a collection fluid on the second
surface of the membrane contactor. In another aspect, the method further
comprises the step of monitoring a change in the pH, ionic strength,
oxidative state, electrical resistance, charge, or contamination of the
oil-containing liquid to determine the removal of gas and oil from the
oil-containing liquid. In another aspect, the method operates at 5, 10,
20, 30, 40, 50, 60, 70, 80, 90, 95, 5 to 95, 10 to 90, 20 to 80, 30 to
70, 40 to 50, 5 to 15, 10 to 30, 20 to 40, 40 to 60, 50 to 70, 60 to 80,
80 to 90, or 90 to 95 psi. In another aspect, the method further
comprises the steps of determining the step of monitoring a change in the
pH, ionic strength, oxidative state, electrical resistance, charge, or
contamination of the oil-containing liquid and depending on the change
adding one or more ions, antibiotics, oxidizers, reducers, surfactants,
detergents, chelators, hydrophilic liquids, hydrophobic liquid, acids, or
bases.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a more complete understanding of the features and advantages of
the present invention, reference is now made to the detailed description
of the invention along with the accompanying figures and in which:

[0015] FIG. 1 is a schematic showing the method and the algal oil recovery
principle as described in the embodiments of the present invention;

[0016] FIG. 2 is a schematic of a general algal oil production process;

[0017] FIGS. 3A and 3B shows photographs of an algal cell prior to (3A)
and after lysing (3B);

[0023] FIG. 8 is a HPLC trace (chromatogram) of oil obtained using hollow
fiber membrane recovery of oil from a lysed suspension of Nanochloropsis.
Two main peaks are seen in this sample, the first is a mixture of various
long chain hydrocarbons and the second is a triglyceride;

[0024] FIG. 9 shows an alternative process where a solid-liquid-liquid
emulsion potentially derived from a dispersive extraction is fed to the
shell-side of the microporous hollow fiber membrane for the purpose of
separating the two liquids;

[0025] FIG. 10 is a schematic showing the method and the oil/water
separation principle for recovery/removal of oil from an oil/water
mixture as described in the embodiments of the present invention;

[0026] FIG. 11 is a schematic showing the method and the oil/water
separation principle for exclusion of water from a water/oil mixture;

[0027] FIG. 12 is a flow diagram of the equipment used to create oil water
mixtures and separate it;

[0028] FIG. 13 is an example of oil/water separation from a ˜12% oil
in water mixture without a recovery fluid;

[0029] FIG. 14 is a comparison of oil/water separation with and without a
recovery fluid;

[0030] FIG. 15 is an example of oil flux through the tubes of the membrane
with and without a recovery fluid;

[0031] FIG. 16 is an example of the relationship between pressure and flux
rate for oil;

[0032] FIG. 17 is an example of oil removal from oilfield waste water
without a recovery fluid;

[0033] FIGS. 18A and 18B are examples of water exclusion from oil.

[0034] FIG. 19 shows Produced water with 10-15 mg/L iron content was
filtered on a 12 uM glass filter to remove insoluble iron (A, left);
water treated with the membrane develops new insoluble iron more slowly
(A, center), as the oxygen content of the water is lowered by treatment
with the membrane (A, right).

[0035] FIGS. 20A and 20B are images showing simultaneous oil and gas
removal. Bubbles are evident in the tube side collection line (20A) and
tube side flow meter (20B) during operation.

DETAILED DESCRIPTION OF THE INVENTION

[0036] While the making and using of various embodiments of the present
invention are discussed in detail below, it should be appreciated that
the present invention provides many applicable inventive concepts that
can be embodied in a wide variety of specific contexts. The specific
embodiments discussed herein are merely illustrative of specific ways to
make and use the invention and do not delimit the scope of the invention.

[0037] To facilitate the understanding of this invention, a number of
terms are defined below. Terms defined herein have meanings as commonly
understood by a person of ordinary skill in the areas relevant to the
present invention. Terms such as "a", "an" and "the" are not intended to
refer to only a singular entity, but include the general class of which a
specific example may be used for illustration. The terminology herein is
used to describe specific embodiments of the invention, but their usage
does not delimit the invention, except as outlined in the claims.

[0038] As used herein, the term "aqueous slurry" encompasses water based
liquids containing any of the following in any combination; insoluble
oils (hydrocarbons and hydrocarbon-rich molecules of commercial value),
living, dead, damaged and/or broken cells (or not), proteins and other
cellular debris, including sugars, DNA, RNA, etc. The slurry may also
contain a solvent that was used to pre-treat cells to liberate compounds
of interest.

[0039] As used herein, the term "oil" refers to a single hydrocarbon or
hydrocarbon-rich molecule including a complex mixture of lipids,
hydrocarbons, free fatty acids, triglycerides, aldehydes, etc. The term
oil also includes, e.g., C8 (jet fuel compatible), C60 (motor
oil compatible) and oils that are odd- or even-chain oils (and mixtures
thereof), e.g., from C6 to C120. Some compounds are pure
hydrocarbons, some have oxygen. Oil also comprises hydrophobic or
lipophilic compounds.

[0040] As used herein, the term "pumping" includes all methods of pumping,
propelling, or feeding fluid from one location to another employing
hoses, lines, tubes, ducts, pipes, or pipelines including under pressure.
It also includes gravity flow of fluid.

[0041] Unlike the prior art, the present invention is based on the
discovery that it is possible to feed two immiscible liquids on one side
of a hollow fiber membrane, e.g., the shell-side, to cause separation of
oils using coalescence versus liquid extraction. By contrast, the prior
art, e.g., U.S. Pat. Nos. 3,956,112; 5,252,220; and 6,436,290, are
feeding one immiscible liquid on the shell side.

[0042] U.S. Pat. No. 3,956,112, issued to Lee, et al., is directed to a
membrane solvent extraction. Briefly, this patent is said to describe a
membrane solvent extraction system that is used to separate a dissolved
solute from one liquid referred to as the carrier and into a second
liquid, which is immiscible with the carrier and is referred to as the
solvent. Therefore, the hollow fiber membrane is used to extract a solute
through a solvent swollen membrane from one solvent liquid phase to the
extracting solvent liquid with direct contact between the liquid phases
only within the porous walls. The membrane extraction method has
potential advantages over conventional solvent extraction in that it does
not require a density difference and provides a large amount of contact
area. The membrane extraction contactor and may be applied to molecular
diffusion based mass transfer separation processes as the mechanism in
separation, purification, pollutant removal and recovery processes. The
Lee patent relies on liquid extraction, as the solvent swells the
membrane filling the pores and providing a diffusional process to extract
a dissolved solute from an immiscible liquid carrier.

[0043] The present invention uses coalescence to achieve the transfer of
oil across the membrane, the component to be removed is essentially
insoluble in the feed and we are recovering only the insoluble liquid. In
liquid extraction, the component to be removed is dissolved in the feed
and the dissolved material is recovered.

[0044] In the present invention, the second immiscible liquid
(hydrocarbon) is removed from the aqueous feed by coalescence on the
surface of the fiber. By contrast, the prior art is removing a dissolved
solute (possibly a hydrocarbon).

[0045] Finally, unlike the prior art, the present invention does not rely
on diffusional mass transfer, but rather, wettability of the insoluble
liquid on the fiber. The liquid extraction of the prior art relies on
liquid-liquid partitioning, diffusional mass transfer and mass transfer
resistances.

[0046] In conventional liquid-liquid extraction and coalescing processes
involving large drops of oil (greater than 1,000 microns), the mixing and
separation of the oil and water phases by a dispersive process is
routinely practiced with relative ease. However, when the oil drops are
significantly smaller in diameter (less than 10 microns) and solids are
present, the complete separation of the immiscible liquids is extremely
difficult, if not impossible using dispersive methods routinely practiced
for larger oil droplets. When routine methods are applied to try to
recover small oil droplets from water in the presence of solids (such as
cells or cell debris), a solid-liquid-liquid emulsion layer is created
resulting in an incomplete and inefficient separation of the two liquids.
Therefore a new process is required that will allow for a more efficient
separation and elimination of the solid-liquid-liquid-emulsion problem.
The process of the present invention enables the recovery of micron and
submicron sized insoluble oil drops from an aqueous slurry utilizing a
novel non-dispersive process.

[0047] A non-dispersive process promotes a one-way flow of specific
compounds into and through a membrane to remove the compounds from the
shell side feed to the tube side. A non-dispersive separation process is
currently used to remove dissolved gases from liquids such as the removal
of dissolved oxygen from water to produce ultra pure water for the
microelectronics industry. The present invention is a first successful
demonstration of the application of non-dispersive processes to recover
insoluble oil from water or aqueous slurries. The non-dispersive process
disclosed herein uses a microporous hollow fiber membrane composed of
hydrophobic fibers. The aqueous slurry containing the insoluble oil is
fed on the shell-side of the hollow fiber module and a
hydrocarbon-appropriate liquid, for example, a biodiesel, or similar oil
recovered in previous application of the described process is fed on the
tube side of the hollow fiber module as a recovery fluid. The aqueous
phase passes around the outside of the large surface area of hydrophobic
fibers containing the hydrophobic recovery fluid as it passes through and
eventually out of the module. As the aqueous liquid with the insoluble
oil drops passes through the module, the insoluble oil droplets coalesce
on to the walls of the hydrophobic fibers and dissolve into the
hydrocarbon-appropriate recovery fluid on the tube side of the module and
are carried out of the module with the recovery fluid. In this process,
the tube side recovery fluid does not make prolonged contact with the
aqueous phase or disperse into the aqueous phase. The absence of this
mixing as hypothesized by the inventors prevents the formation of a
solid-liquid-liquid emulsion, when solids were present, allowing
insoluble oil to be recovered efficiently from an aqueous slurry
containing solids. The above hypothesis was successfully demonstrated
herein to efficiently recover insoluble oil from an aqueous mixture
including cells without the formation of a solid-liquid-liquid emulsion.

[0048] In typical membrane filtration processes, small amounts of solids
quickly build up on the surface of the membrane (commonly called membrane
fouling) reducing the efficiency and cost effectiveness of the filtration
process. In the process discovered and disclosed herein using the
microporous hollow fiber membrane module, membrane fouling is not a
concern within specific operating parameters. The present invention shows
that if the module is operated using hydrophilic cells that are small
enough to pass through the dimensions of the module, and an appropriate
pressure differential is maintained between the aqueous fluid and
recovery fluid, then the hydrophilic cells flow through the module and
are repelled from the surface of the membrane because the membrane is
coated with a hydrophobic recovery fluid. The results presented herein at
the prescribed operating conditions do not indicate any evidence of
membrane fouling.

[0049] The novel recovery process of the present invention utilizes a
non-dispersive method to coalesce and recover an insoluble oil from an
aqueous slurry. The technique utilizes a microporous hollow fiber
membrane contactor. The inventors have tested the Liqui-Cel Extra Flow
Contactor, commercially used for gas/liquid contacting, to obtain >80%
recovery efficiency and process concentrates up to 10% bio-cellular
solids without membrane fouling. The novel technique of the present
invention utilizes the large coalescing area provided by the surface of
the microporous hollow fibers when filled with a hydrophobic recovery
fluid and minimizes the actual contact of the solvent with the (e.g.
yeast) biomass and aqueous phase.

[0050] The novel recovery process described herein can be coupled with a
variety of appropriate recovery fluids for recovery of insoluble
compounds, depending upon the types of compound or compounds to be
recovered. The choice of recovery fluid will impact both the sub-set of
compounds recovered from the aqueous slurry as well as the downstream
steps needed to economically and efficiently use compounds from the
recovery fluid. Differential recovery of desired molecules, for example,
recovery of non-polar oils, but not more polar oils, can be achieved by
choice of recovery fluid. Segregation of non-polar oils from polar oils,
specifically polar oils containing phosphorous (e.g., phospholipids), is
highly advantageous as phosphorus containing compounds complicate both
the refining and transesterification processes used to create
transportation fuels.

[0051] Downstream steps needed to recover desired molecules from the
recovery fluid are also application specific. If heptane is used as the
recovery fluid, compounds of interest may be recovered by distillation
without the need of a steam stripper. If biodiesel (Fatty Acid Methyl
Ester [FAME]) is used as the recovery fluid, e.g., recovered oils may not
require processing prior to transesterification to FAME. Importantly, the
present invention can also uses a "self" oil that has been previously
recovered from an aqueous slurry as the recovery fluid thereby completely
eliminating the need and expense of having to separate the recovered
compounds from the recovery fluid. In this application, the recovery
fluid is a quantity of oil derived from previously processed aqueous
slurry or extracted by a different method. The microporous hollow fiber
membrane contactor as described in the present invention is small,
portable, economical and is capable of handling large aqueous slurry feed
rates.

[0052] In another embodiment, the present invention describes a method of
recovering one or more hydrocarbons or hydrocarbon-rich molecules (e.g.,
farnesene, squalane, aldehydes, triglycerides, diglycerides, etc.) or
combinations thereof, from an aqueous preparation using one or more
hydrophobic membranes or membrane modules. Without limiting the scope of
the invention, an example includes recovery of hydrocarbon and
hydrocarbon-rich molecules produced by microbial fermentation. Microbial
fermentation processes are described in which organisms including algae,
yeast, E. coli, fungi, etc. are used to metabolize carbon sources (e.g.,
sugars, sugarcane bagasse, glycerol, etc.) into hydrocarbons and
hydrocarbon-rich molecules that are secreted from (or accumulate within)
the cells. Such organisms are expected, by design, to produce physically
small oil droplets; the inventors hypothesized that these droplets will
not readily resolve from water by gravity alone and that the process
described herein will be immediately applicable to recover insoluble oils
produced by microbial platforms. The companies commercializing microbial
fermentation to oil technologies have implied that the recovery of the
oil product is trivial, but emerging company disclosures and scientific
data suggest recovering the oil from the aqueous growth media is a
mission-critical problem. Technologies currently in use, for e.g.
centrifugal force sufficient to pellet E. coli cells are not sufficient
to break the oil/water emulsion that is created in the aqueous growth
media by the hydrocarbon-producing E. coli.

[0053] In addition to the steps listed herein above the method of the
present invention further involves the steps of collecting the one or
more recovered algal lipid components, algal oils or both in a collection
vessel, recycling the separated solvent by pumping through the one or
more membranes or membrane modules to process a subsequent batch of lysed
algae, converting the one or more recovered algal lipid components, algal
oils or both in the collection vessel to Fatty Acid Methyl Esters (FAMEs)
or a biodiesel by transesterification or alternatively, refinery-based
processing such as hydrocracking or pyrolysis, and processing the first
stream comprising the algal biomass by drying the algal biomass to be
optionally used as animal feed, feedstock for chemical production, or for
energy generation. In the event one or more solvents are used as the
recovery fluids, the method includes an optional step for separating the
one or more recovered algal lipid components, algal oils or both from the
one or more solvents. The lysed algal preparation used in the method of
the present invention comprises a concentrate, a slurry, a suspension, a
dispersion, an emulsion, a solution or any combinations thereof.

[0055] In yet another aspect of the method of the present invention, when
using one or more counterflowing recovery fluids, these may comprise
hydrophobic liquids, alkanes such as hexane, aromatic solvents such as
benzene, toluene, ethers such as diethyl ether, halogenated solvents such
as chloroform, dichloromethane, and esters such as ethyl acetate. In one
aspect the counterflowing non-polar oil comprises algal oils, components
of biodiesels selected from monoglycerides, diglycerides, triglycerides,
and fatty acid methyl esters.

[0056] The present invention describes a method for recovering algae oil
from lysed algae concentrate using hydrophobic microporous hollow fiber
membrane followed by recovery of the algal oil using a recovery fluid
which can be a solvent, a hydrophobic liquid, a biodiesel, an algal oil
or mixtures thereof. The technique of the present invention does not
require dispersive contacting of the lysed algae concentrate and recovery
fluid. The use of a hydrophobic microporous hollow fiber membrane
provides a non-dispersive method of coalescing and recovering the algal
oil. The lysed algae concentrate is fed on the shell side while algal oil
or the recovery fluid is fed on the fiber side. The recovery fluid acts
to sweep and remove the coalesced oil within the tube surface of the
hollow fibers. A simple schematic representation of the method of the
present invention is depicted in FIG. 1.

[0057] FIG. 1 shows an algal oil recovery unit 100. The unit 100 comprises
a housing 102, within which is contained a membrane module 104 comprising
a plurality of microporous hollow fiber membrane units depicted as 104a,
104b, and 104c. The unit has two inlet ports 106 and 108. The lysed algal
preparation is fed (pumped) through port 106. A recovery fluid is pumped
through inlet port 108. The recovery fluid can be a solvent, a biodiesel,
an algal oil or mixtures thereof. The algal preparation counterflows with
the recovery fluid flowing inside the microporous hollow fiber membranes
104a, 104b, and 104c. The algal oils or lipid coalesce on the surface of
the hollow fiber membranes and are swept by and recovered by the recovery
fluid and exit the unit 100 through the outlet port 110. The exit stream
is taken for further processing (e.g. solvent recovery) if necessary. The
recovery fluid flows out of the unit 100 through port 112.

[0058] The method of the present invention using a compatible mixture as
the recovery fluid eliminates the need of a distillation system or a
stripper to recover the solvent thereby reducing the capital and
operating cost of the overall oil recovery process.

[0062] While algae make oil there is no simple and economical method for
extracting the oil directly from an aqueous slurry. Drying algae is
usually needed for solvent extraction and the biomass is exposed to toxic
solvents. Other methods such as supercritical extraction are uneconomical
for commodity products such as fuel. Solvent extraction is somewhat
promising but requires distillation of an extract to separate the solvent
from the oil. Also, a steam stripper is usually required to recover the
residual solvent dissolved or entrained within the exiting algal
concentrate. The solvent extraction technique requires contactor
equipment or phase separation equipment, a distillation system and a
steam stripper along with varying heat exchangers, surge tanks and pumps.
Also steam and cooling water are required. The process described herein
only requires a membrane system with pumps and tanks; the oil is
coalesced, not extracted. No steam or cooling water is required.

[0063] Processing Alternatives: After selection of the appropriate
solvent, the next step is to determine whether to extract algae oil from
"wet" or "dry" algae. The "dry" process requires dewatering and
evaporating the water from the algae biomass and then lysing the algae.
Lysing is a process of breaking the cell wall and opening the cell.
Solvent may be contacted with the dry algae in special counter current
leaching equipment. The solvent and extracted algae oil is separated in a
vacuum distillation tower or evaporator. The remaining algae biomass with
residual solvent is fed to a special evaporator to remove and recover the
solvent and to dry the algae biomass again. The "dry" process suffers
from having to dry the algae a second time when the solvent must be
evaporated away, handling a high solids stream in multiple steps, and
potentially leaving solvent in the residual algae solids.

[0064] The "wet" process requires lysing and extraction of the algae
concentrate. The wet process requires an excellent lysing technique
followed by a solvent extraction process, which provides adequate mass
transfer area for dissolving/coalescing the non-polar lipids. The "wet"
process offers the advantages of drying the algae only once and leaving
less residual solvent in the algae biomass. To minimize the processing
cost, the "wet" process appears to offer significant advantages.

[0065] The present invention focuses on the "wet" process and the novel
non-dispersive contactor used to coalesce and dissolve the desirable
non-polar lipids.

[0066] As shown in FIG. 2 a complete extraction process 200 begins with
the oil extraction step 212 followed by the algae concentration 208 and
lysing 210 steps. After growing and initial harvesting under sunlight
204, from the pond 202 the dilute algae feed is concentrated
significantly. The microbes such as the algae, media and/or water are
returned at step 214. The typical algae concentration obtained from the
pond 202 generally ranges from 100 to 300 mg dried algae/liter of
solution. The goal of the concentration step 208 is to remove and recycle
the water 214 back to the pond. Concentration methods 208 vary from
centrifugation to flocculation/settling of the algae. To maximize lysing
and oil recovery efficiency, it is important that concentrate being fed
for lysing is not flocculated. After the concentration step 208, the
algae concentrate is sent to the lysing 210 processing step where the
algae cell is mechanically or electromechanically broken, thus exposing
and freeing the non-polar oil. Various techniques may be used to
mechanically or electrically compress and decompress to break the cell.
In general after lysing, 212 the algae cell can be disintegrated or
opened-up as shown in FIG. 3. FIGS. 3A and 3C shows photographs of an
alga cell prior to lysing and FIGS. 3C and 3D show photographs of algal
cells prior after lysing.

[0067] Once the oil has been freed from inside the algae cell, the oil
will not simply separate from the cellular biomass due to density
differences. Also since the equivalent diameters of most microalgae are
extremely small and on the order of 1-5 microns, the oil drop diameter is
often much less than 1 micron. Such oil drops do not rise or coalesce
with other drops very well and can form a stable emulsion. When solid
algae biomass 216 is added to the mixture, the recovery of the oil is
even more difficult. Therefore simple gravitational phase settling is not
a viable oil separation option after lysing.

[0068] After lysing, the algae concentrate is fed to the separations step
212 where algae oil 220 is separated from the wet algal biomass 216 to
produce fuel 214. The biomass 216 may be sent for further drying and will
be used for animal feed or processed further for energy generation
applications.

[0069] As shown in FIG. 4, the typical solvent extraction process involves
1) an extraction step to recover algae oil from the lysed biomass, 2) a
vacuum distillation or evaporation step to separate the oil and solvent
where the solvent is returned to step 1, and 3) if necessary, steam
stripping step to recover the dissolved and entrained solvent leaving the
extraction step with the algal biomass.

[0070] FIG. 4 a flow diagram 400 of a general algae oil extraction process
using a conventional dispersive extraction column 406. Lysed algal
concentrate 402 and solvent 404 is fed to a column extractor 406 to
extract the algal oils and lipids 408. Stream 406a comprises the solvent
404 containing the algal oils and lipids. Stream 406a is then fed to a
vacuum distillation unit 408 to recover the solvent 404 and the algal oil
410. The separated solvent without any oil or other constituents 404 is
fed back to the extractor 406. In the event it needs further purification
(separation), the solvent 404 is fed back to the vacuum distillation unit
408 (via stream 408a). A second stream 406b from the extractor 406
comprises the algal biomass, solids, and residual solvent. Stream 406b is
passed through a stream stripper 412, to separate the wet biomass 418 and
other solids from the solvent 404. The wet biomass 418 is subjected to
further drying. The recovered solvent 414 is collected in a decanting
vessel 416 before being recycled 420 back to the extractor 406 via stream
414a and can be controlled with valve 424. A second stream 414b from the
vessel 416 recycles any dissolved solvent in condensed steam 414 back to
the stream stripper 412.

[0071] Extraction Processing and Equipment: The desired extraction process
for algae oil recovery must satisfy certain requirements and avoid
potential deficiencies for economic recovery. There are several "wet"
extraction processes for oil recovery that are technically feasible but
are not necessarily economical. Minimal oil recovery costs are critical
if the ultimate use of the recovered algae oil is fuel.

[0072] The optimum oil extraction process should include: (i) processing a
bio-cellular aqueous slurry containing oil, (ii) using a non-polar
solvent or extracted oil with extremely low miscibility in water, (iii)
using a solvent (if necessary), that easily separates from the oil, (iv)
using extraction equipment that can handle high processing feed rates and
easily scaled-up, (v) using extraction equipment that minimizes the
entrainment of solvent into the biomass, (vi) using extraction equipment
that provides a high contact area for mass transfer and non-polar lipid
coalescence, (vii) using extraction equipment capable of handling
concentrated algae feeds and not be irreversibly fouled by algae solids,
(viii) using extraction equipment that is relatively compact and
potentially portable to allow transport to different algae production
sites, and (ix) using extraction equipment that is readily available,
inexpensive and safe.

[0073] Membrane based processes for separations have been in existence for
a long time. There are many types of membranes. Most membrane processes
however use porous membranes wherein the membrane material performs a
separation as a result of differences in diffusion and equilibrium
between chemical components and on the molecular level. The present
inventors however utilize a microporous membrane, which is used
commercially in applications involving the transfer of gases to or from a
liquid such as water. The microporous membranes function very differently
from the porous membrane because of their relatively large pores. The
microporous membranes do not truly separate chemical components on the
molecular level like porous membranes do. The present invention relies on
the coalescence of non-polar lipids present within the algae slurry to
coalesce onto the hydrophobic surfaces provided by the hollow fibers. The
vast surface area of the membrane, combined with the hydrophobic recovery
fluid's ability to wet the membrane, creates a surface capable of
coalescing small lipid droplets. Once coalesced into the recovery fluid,
the lipids are transported out of the membrane through the inner tubes of
the hollow fibers.

[0074] Membrane based Oil Recovery Process: For example, the application
of a microporous hollow fiber (MHF) membrane contactor as the optimal
separation equipment appears ideally suited for the recovery of algae
oil. The MHF contactor provides all of the optimum characteristics listed
previously. The application MHF contactor to algae oil recovery is novel,
minimizes solvent loss, eliminates need for the steam stripper, minimizes
solids contamination, and is easy to operate. The process does not
involve dispersing a solvent into the algae biomass. The non-dispersive
nature of the contactor is attractive in minimizing solvent loss and thus
potentially eliminating the need for a steam stripper. A recovery fluid
typically comprising of either a solvent (such as hexane) or a
hydrophobic liquid, or algal oil is circulated through the hollow fibers
for the recovery of the algal oils. The application of the MHF contactor
in conjunction with a recovery fluid circulated through the microporous
hollow fibers eliminates the need for a solvent and distillation column.
The two oil extraction processing schemes with solvent and the recovery
fluid are shown in FIGS. 5 and 6, respectively.

[0075] FIG. 5 is a schematic 500 depicting the novel algal oil recovery
process (with solvent) of the present invention. The process comprises a
MHF contactor 502 comprising a plurality of microporous hollow fiber
membranes 504 and a central baffle 506. Solvent 508 is fed (pumped)
through the membrane fibers 504 and is contacted with the lysed algal
concentrate 512 contained in the shell portion of the MHF contactor 502.
There are two exit streams from the contactor 502, an algal biomass
stream 510 which is processed further (dried) and a solvent stream 508a
which contains the recovered algal oils and lipids 516. The stream 508a
is passed through a vacuum distillation unit 514 to separate the oil 516
from the solvent 508 and to recover the solvent 508 for recycle and
reuse. Exit stream 508b from the distillation unit 514 comprises pure
solvent 508 which is recycled and fed to the contactor 502 to repeat the
process and solvent requiring further separation and is recycled back to
the distillation unit 514. Exit stream 508c from the distillation unit
514 comprises the algal oils 516. A portion of this stream is vaporized
(518b) and returned to the distillation unit 514.

[0076] FIG. 6 is a schematic 600 depicting the novel algal oil recovery
process of the present invention. The process comprises a MHF contactor
602 comprising a plurality of microporous hollow fiber membranes 604 and
a central baffle 606. Non-polar algae oil 608 is fed (pumped) through the
membrane fibers 604 and is contacted with the lysed algal concentrate 612
contained in the shell portion of the MHF contactor 602. The non-polar
algae oil functions to dissolved and sweep the coalesced oil from the
algae concentrate. The non-polar oil 616 coalesces onto the hydrophobic
fiber surface 604 and dissolves into oil contained in the walls and the
counterflowing oil phase 608 and can be removed. There are two exit
streams from the contactor 602, an algal biomass stream 610 which is
processed further (dried) a stream 608a which contains the algal oils and
lipids 616 that is collected in a tank 614. Part of the oil 616 can be
removed from the tank 614 and fed to the contactor 602 to repeat the
process.

[0077] Microporous hollow fiber contactors were initially developed in the
1980s. These early studies focused on lab-scale prototype modules
containing just a few fibers. These early studies promoted the
possibility of liquid-liquid extraction applications. The contacting of
two immiscible liquids such as water and a non-polar solvent is unique
with MHF contactors in that there is no dispersion of one liquid into
another. This technology is sometimes referred to as non-dispersive
extraction. The hollow fibers are generally composed of a hydrophobic
material such as polyethylene or polypropylene. These hollow fibers could
be made of a different material but it should be hydrophobic to avoid
fouling of the fiber surface with the algae solids which are usually
hydrophilic. The solvent should be a hydrocarbon with a very low
solubility in water and is pumped through the hollow fibers. As a result
of the hydrophobicity of the fiber material, the solvent will wet the
microporous fibers and fill the micropores. The aqueous-based fluid is
pumped through the shell-side of the membrane contactor. To prevent
breakthrough of the solvent into the shell-side, the shell or aqueous
side is controlled at a higher pressure than the fiber or hydrocarbon
side. This results in immobilizing a liquid-liquid interface in the
porous walls of the hollow fibers. Unfortunately when these modules were
scaled-up for liquid-liquid extraction, the performance was usually
disappointingly poor. Further studies identified the poor efficiency was
a result of shell-side bypassing. An improved version (referred to as the
Liqui-Cel Extra Flow contactor) was developed which eliminated the
possibility of shell-side bypassing by incorporating a shell-side
distributor. While the design eliminated the shell-side bypassing, the
new design eliminated true counter-current contacting. The overall
performance was improved somewhat relative to the original design.
Nevertheless, the new design did not correct the fundamental limitations
of pore-side mass transfer resistance that would control most
commercially significant extraction applications. As a result, only a few
commercial liquid extraction applications using MHF contacting technology
exist today.

[0078] Also, the MHF contactors often required expensive filter systems to
avoid plugging with solids associated with most commercial liquid-liquid
extraction processes. The Liqui-Cel contactor used in the present
invention has been applied almost exclusively to commercial processes
that transfer a gas to or from a liquid such as oxygen stripping from
water for the microelectronics industry.

[0079] No applications of the MHF contactors are known for enhancing
coalescence and removing of oil drops from water. Certainly no
applications of MHF technology are known for oil recovery from water
involving a significant solids concentration.

[0080] FIG. 7 is a schematic 700 of the Liqui-Cel extra flow microporous
hollow fiber membrane contactor 702. The contactor 702 comprises a
metallic or polypropylene housing 706, wherein is contained a cartridge
708 comprising a plurality of hydrophobic microporous hollow fibers 712,
along with a distribution tube 710, a collection tube 716, and a central
baffle 714. The housing 706 has 2 inlet ports (704a and 704b) and two
outlet ports 704c and 704d.

[0081] As shown in FIG. 7, the aqueous phase 718 is fed through the port
704a on the shell-side while the solvent (or oil) phase 722 is fed on the
fiber side through port 704b. The non-polar lipids coalesce onto the
hydrophobic surface and wet and dissolve into walls and into the
counterflowing solvent (or oil) phase. A higher pressure is maintained on
the aqueous side to prevent bleed through of the solvent (or oil) phase.
However the shell-side pressure is kept below the breakthrough pressure
which forces aqueous phase 718 into the solvent (or oil) phase 722. The
algae concentrate 718 and solvent feeds 722 could be operated at room
temperature or preheated up to 60° C. The solvent (or oil) phase
along with the recovered lipids or oils is removed through outlet port
704c, and the aqueous algal raffinate containing the algal biomass and
other solids is removed through the port 704d.

[0082] While not intuitive because of the presence of algae solids, the
MHF contactor appears ideal for recovering oil from lysed algae. The MHF
contactor provides: (i) high contact area for coalescence and mass
transfer, (ii) processing of un-flocculated or deflocculated algae
solids, (iii) large flow capacities on the shell side, (iv) negligible
mass transfer resistance in the pore because of the high equilibrium
distribution coefficient of non-polar oils into non-polar solvent, and
(v) low cost per unit of algae flow per unit as the contact area is
100× that for the conventional liquid extraction contactor (e.g.
perforated plate column).

[0083] The MHF contactor provides four significant advantages: (i) no
density difference is required, (ii) no entrainment of solvent which may
eliminate the need for a stripping column when the proper solvent is
selected, (iii) easy control of the liquid-liquid interface by
controlling the pressures, (iv) extremely large area for coalescence of
small algae oil drops. The MHF contactor functions primarily as an oil
coalescer. The solvent acts to simply remove the coalesced oils from the
surface of the fibers, and (v) while not optimized, commercial MHF
contactor modules used for gas transfer are available and reasonably
priced. The Liqui-Cel Extra Flow contactor is a good example.

[0084] MHF Contactor Performance Data: The present inventors characterize
the performance of the MHF contactor for algal oil recovery. The
objectives of the studies were to determine the fraction of non-polar
algae recovered from the feed and determine if membrane plugging was
observed. The 4-inch diameter Liqui-Cel Extra Flow Contactor, purchased
from Membrana [Part#G503], was used to recover algae oil from an actual
lysed algal concentrate (FIG. 7). Typical oil recoveries from
experimentally lysed algae ranged from 45->80% for a single module.
The results of the studies are shown in Table 1. Differences in oil
recoveries may be attributed to the lysing efficiency, polarity of the
algae oil, differences in oil wettability and coalescence onto the
membrane fibers. Membrane plugging is not observed when processing lysed
algae concentrates where the algae is not flocculated or has been
deflocculated. A typical range of conditions associated with the recovery
of non-polar algae oil is shown in Table 1. These data are based on the
processing of actual lysed algae. Since the non-polar oil recovery
efficiency is also affected by the lysing efficiency, controlled
experiments were carried out where known quantities of canola oil were
injected into a re-circulating algae concentrate stream. In the first set
of studies, heptane was re-circulated on the tube side as a non-polar oil
specific recovery fluid. The results of these studies are shown in Table
2. In the initial small scale studies, 44-64% of the injected oil volume
was recovered by the microporous hollow fiber membrane when only 25 mLs
of canola oil was injected. When a larger quantity of canola oil was
injected (250 mL), more than 90% of the injected oil volume was recovered
as shown in Table 2. These data provide evidence that a fixed volume of
oil is likely held up in the walls of the hollow fibers. In a second set
of studies using canola oil injected into lysed algae concentrate, canola
oil was re-circulated through the hollow fiber tubes as a recovery fluid
instead of heptane. As shown in Table 3, 93% of the 9 liters of injected
canola oil was recovered, conclusively demonstrating that a "like" oil
can be used as a recovery fluid. The second set of studies validates the
mechanism that the process is based on coalescing and recovery of the oil
drops from the aqueous slurry can be done using a "like" oil. The canola
oil runs also provide supporting data for the application of the
non-dispersive microporous hollow fiber technology in removing residual
oil from produced water, as canola oil/water emulsions are an accepted
experimental proxy to mimic produced water in a laboratory setting. The
results from Tables 2 and 3 indicate that oil recoveries approaching 100%
are possible. The walls of the hollow fibers will always contain oil
during processing.

[0085] It should be noted that the algae concentrate feed or bio-cellular
feed must not contain flocculated algae or solids to prevent plugging
within the membrane module. For the case of the MHF contactor described
in the present invention, the minimum dimension for shell-side flow is 39
microns which is greater than the size of most single alga. It is likely
that flocculated algae will eventually plug the shell-side of the MHF
contactor.

[0086] In a related and alternative process, the microporous membrane
could be used to separate two liquids from a solid-liquid-liquid
emulsion. The solid-liquid-liquid emulsion may have been derived from a
process for recovering oil from a bio-cellular aqueous feed using a
dispersive process. The microporous membrane hollow fiber contactor would
allow the hydrocarbon liquid to "wet" and coalesce into the walls of the
hollow fibers while preventing the hydrophilic solids or aqueous phase
from entering. Thus the hydrocarbon liquid will exit the membrane on the
tube side when an appropriate recovery fluid is employed, while the
aqueous liquid and solids will exit on the shell-side. An alternative
process is shown in FIG. 9.

[0087] The flow diagram 900 shown in FIG. 9 of the alternative algae oil
extraction process comprises a dispersive extraction column 902, lysed
algal concentrate 904 and solvent 908 is fed to a dispersive extractor
such as a column extractor, centrifugal type extractor or mixer-settler
902. The solid-liquid-liquid emulsion (S-L-L) 912 from the column 902
comprising algae-water-solvent is then fed to a shell-side of a
microporous membrane extractor (contactor) 910. Any solids (algal
biomass) from the column extractor 902 may be directly subjected to
further processing (e.g. drying) as shown by step 914. The microporous
membrane hollow fiber contactor 910 allows the hydrocarbon liquid to
"wet" and coalesce into the walls of the hollow fibers while preventing
the hydrophilic solids or aqueous phase from entering. The hydrocarbon
liquid exits the membrane contactor 910 on the tube side when an
appropriate recovery fluid (for e.g. solvent 908) is employed on the tube
side, while the aqueous liquid and solids (algal biomass) will exit on
the shell-side for further processing (e.g. drying) as shown by step 914.
The hydrocarbon liquid is then fed to a distillation unit 916 (heat
exchangers associated with the distillation unit are shown as 918 and
920) for removal of any residual solvent 906 and to recover the algal oil
924. The recovered solvent 906 may be circulated back into the process,
for e.g. as the recovery fluid on the tube-side of the membrane contactor
910 or back to the dispersive extraction column 902.

[0088] The recovery fluid on the tube side can be tailored to enhance
recovery or selectively recover sub-sets of desired compounds, and leave
others. Study data demonstrates that hydrocarbons and non-polar lipids
are removed using heptane or like oil and phospholipids are not.

[0089] To determine the composition of the recovered oil, the inventors
performed a normal phase HPLC using a Sedex 75 evaporative light
scattering detector. As shown in FIG. 8, two main components were
detected in this particular sample of oil, the first peak corresponding
to long chain hydrocarbons and the second corresponding to triglycerides.
In some samples, 1,3 and 1,2 diglyceride have also been detected.

[0090] FIG. 10 is a schematic showing the method and the oil/water
separation principle for recovery/removal of oil from an oil/water
mixture as described in the embodiments of the present invention. In this
mode of operation the present invention can be used for most oil/water
mixtures that are up to ˜90% oil by volume. The oil-water mixture
emanating from the shell side may be further processed, for example with
an additional contactor. In this embodiment, an oil/water mixture 1102
enters the membrane contactor 1100 and the oil coalesces on a first
surface of the membrane contactor 1100. A recovery fluid 1104 that is in
contact with a second surface of the membrane contactor 1100 collects
coalesced oil 1108.

[0091] An oil/water mixture without the coalesced oil 1106 and recovered
exits the membrane contactor 1100 and can be further processed by
contacting with the same or a different membrane contactor (not shown).

[0092] FIG. 11 is a schematic showing the method and the oil/water
separation principle for exclusion of water from a water/oil mixture. In
this mode of operation the present invention is appropriate for very low
water content streams. With the shell side outflow capped, the excluded
water will accumulate in the shell side of the module. The tube side oil
outflow rate can be used to indirectly monitor the accumulation of water
in the shell side. As water accumulates, the effective shell side surface
area begins to decrease, leading to reduced tube side flows. Briefly
opening the shell side outflow valve can purge the accumulated water and
return the unit to high efficiency operation. In this embodiment, an
oil>>water mixture 1112 enters the membrane contactor 1100 in which
the oil is the primary portion of the liquid and the water or other
non-oil liquid is a lesser part of the mixture, and the oil coalesces on
a first surface of the membrane contactor 1100. A recovery fluid 1104
that is in contact with a second surface of the membrane contactor 1100
collects coalesced oil 1108. An oil/water mixture without the coalesced
oil 1106 exits the membrane contactor 1100 and can be further processed
by contacting with the same or a different membrane contactor (not
shown). In one embodiment, the amount of oil to water/non-oil liquid,
volume to volume, may be 50:50, 60:40, 70:30, 80:20, 90:10, 91:9, 92:8,
93:7, 94:6, 95:5, 96:4, 97:3, 98:2, 99:1, 99.5:0.5, 99.6:0.4, 99.7:0.3,
99.8:0.2, and 99.9:0.1.

[0093] FIG. 12 is a flow diagram of a membrane contactor system 1200. In
this embodiment, the membrane contactor 1202 is a schematic 1200
depicting a novel oil recovery process of the present invention. The
process comprises a MHF contactor 1202 comprising a plurality of
microporous hollow fiber membranes 1204 and a central baffle 1206. In one
non-limiting example of an oil, non-polar Algae oil 1208 is fed (pumped)
through the membrane fibers 1204 and is contacted with the lysed yeast or
algal oil concentrate 1212 contained in the shell portion of the MHF
contactor 1202. The non-polar oil 1216 coalesces onto the hydrophobic
fiber surface 1204 and dissolves into oil contained in the walls and the
counterflowing oil phase 1208 and can be removed. There are two exit
streams from the contactor 1202, a yeast or algal biomass stream 1210
which is processed further (dried) a stream 1208a which contains the
yeast or algal oils and lipids 1216 that is collected in a tank 1214.
Part of the oil 1216 can be removed from the tank 1214 and fed to the
contactor 1202 to repeat the process. Media, nutrients, additional
organisms (yeast or algae), liquid or other compositions can be provided
from burettes 1219. Multiple pumps and valves may be used to control the
flow of the various liquids and components.

[0094] FIG. 13 is a graph that shows the test results from the recovery of
oil from a mixture created to test for oil recovery in the absence of
recovery fluid at constant pressure. Briefly, 980 mL of oil (isopar L)
was injected per minute into a stream of water flowing at 2 gpm. Oil
volume was recovered directly from the tube side outflow and the volume
of oil recovered was measured at 5 min intervals.

[0095] FIG. 14 is an example of oil/water separation from a ˜12% oil
in water mixture with and without a recovery fluid at constant pressure.
1000 mL of oil was injected into a water stream flowing at 2 gpm. Volumes
of oil recovered were determined using a calibrated sight glass when
recovery fluid was used, and by direct measurement of volume recovered
from the tube side outflow when recovery fluid was not used. With
recovery fluid, the instantaneous recovery is higher in the first minutes
of operation.

[0096] FIG. 15 is a comparison of pure oil flux rates with and without a
recovery fluid. In this study, the test ran at 3 gpm of oil (isopar V) on
the shell side with the shell side outlet open. Volumes of oil recovered
were determined using a calibrated sight glass when recovery fluid was
used, and by direct measurement of volume recovered from the tube side
outflow when recovery fluid was not used. This experiment also shows the
approximately linear relationship between pressure and flux, in which the
flux rate increases with increasing pressure.

[0097] FIG. 16 is an example of oil flux with and without a recovery
fluid. This test demonstrates the flux of pure oil (isopar L) as a
function of pressure in the absence of a recovery fluid. For the 10 and
30 psi points, isopar L was circulated at ˜3 gpm on the shell side
of the membrane. Oil volume was recovered directly from the tube side
outflow. The test proceeded until 4 L of oil was recovered from the tube
side. For the 50 psi dataset, the shell side outflow was capped, forcing
the oil to pass through to the tube side. The test proceeded until 4 L of
oil was recovered from the tube side. The average flux rate of duplicate
runs is shown.

[0098] When considered with the previous figure, this test shows that the
viscosity of the oil is a variable in the flux rate. For example, isopar
L fluxed at a rate of about 5.5 L per min through the membrane at 30 psi.
By contrast, the flux rate of isopar V at 30 psi was about 1 L per min in
the previous test. The difference in flux rates is directly related to
the viscosity of the oils; isopar V (˜17 cSt) is significantly more
viscous than isopar L (˜2 cSt) and fluxes more slowly at identical
operating conditions.

[0099] FIG. 17 is an example of oil recovery from wastewater.
Approximately 5 gallons of oil field wastewater containing light oils and
solids of unknown composition was passed through the contactor to remove
the oil. A recovery fluid was not used. The material was circulated
through a 2.5 inch diameter membrane approximately 10 times with a 30 psi
pressure differential. At the conclusion of the test, the shell side
effluent (A) still contained the solids. A quantity of oil was recovered
from the tube side (B).

[0100] FIGS. 18A and 18B are examples of water exclusion from oil without
a recovery fluid. Approximately 19 liters of isopar L was mixed with 1
liter of water and circulated repeatedly through a pump to create an
emulsion (FIG. 18A, on left). This mixture was passed through a 4 inch
diameter membrane to exclude the water. The shell side inlet pressure was
25 psi and a recovery fluid was not used. Oil volume was recovered
directly from the tube side outflow. The test was stopped once 14 L
isopar L was collected from the tube side outflow (FIG. 18A, on right).
Alternately, the water exclusion process can be run with the shell side
outflow capped; in this case, excluded water accumulates in the shell
side of the membrane. FIG. 18B shows a sample of the remaining volume
from the shell side of the membrane from a similar demonstration; water
is on the bottom and remaining water/oil emulsion is on the top.

[0101] FIG. 19 shows produced water with 10-15 mg/L iron content was
filtered on a 12 uM glass filter to remove insoluble iron (FIG. 19,
left). Following filtration, crude oil was spiked into the filtered water
at a concentration of approximately 100 ppm. A sample of the filtered
water with spiked oil was collected and set aside. The remaining produced
water with spiked oil was passed through the membrane three times to
remove the oil. Approximately 3 hours after the oil was introduced into
the filtered water, the samples of the starting material and the water
treated with the membrane were compared. The formation of insoluble iron
in the water is driven by the presence of oxygen in the water. The
untreated, filtered water steadily develops new insoluble iron over time.
The water treated with the membrane develops new insoluble iron more
slowly (FIG. 19, center), as the oxygen content of the water is lowered
by treatment with the membrane (FIG. 19, right). Oil-in-water analyses
were conducted on samples of the filtered water, filtered water with oil
spiked and the membrane-treated water. Passing the water with spiked oil
through the membrane twice reduced the oil concentration to less than 3
ppm and increased the pH from 7 to 7.5. The increase in pH is consistent
with the removal of CO2 from the water. Table 4 summarizes the results of
the removal of oil in water and the change in pH.

[0102] FIGS. 20A and 20B show the apparatus operating to remove oil from
produced water at an oilfield site. As can be seem clearly in FIG. 20A,
gas is removed from the stream during oil removal as demonstrated by the
bubbles in the tubing. Bubbles continuously appear in the tube side
collection volume with the collected oil, as seen in the tube side
outflow line (20A) and at a flow meter (20B). The produced water stream
was under pressure.

[0103] It will be understood by the skilled artisan that the process
described hereinabove is applicable broadly for insoluble oil recovery
beyond algae to include protists, fungi, yeast, E. coli, etc., mixed
cultures of cells, grown by any method (not limited to photosynthetic
organisms), aqueous slurries or aqueous mixtures containing broken and/or
live cells or no cells (in case pre-treated to remove cells/cell debris
or other suspended materials). The process can also be used to recover
oil from any liquid source comprising insoluble oils for e.g. industrial
water, brine, wastewater, industrial or natural effluents, water-oil
mixtures, aqueous slurries, aqueous slurries comprising broken cells,
live cells or combinations thereof, bio-cellular mixtures, lysed cellular
preparations, and combinations thereof. The process of the present
invention is capable of recovering almost up to a 100% of the one or more
insoluble oils in the liquid source. The process provides insoluble oil
recoveries of 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%,
99% and 100% from the liquid source.

[0104] The method and the process of the present invention can be expanded
for recovery of a variety of molecules depending upon choice of recovery
fluid and to include single or multi-step, differential recovery
processes for e.g., specifically recover non-polar oil with one membrane
module, then treat the effluent with a second membrane module employing a
different recovery fluid. The recovery fluids may be selective, partially
selective or non-selective for specific compounds. In other specific
examples, the present invention may be used to specifically recover
non-polar oil with one membrane module, then followed by treatment of the
effluent from the first module with a second membrane module employing a
different recovery fluid.

[0105] It is contemplated that any embodiment discussed in this
specification can be implemented with respect to any method, kit,
reagent, or composition of the invention, and vice versa. Furthermore,
compositions of the invention can be used to achieve methods of the
invention.

[0106] It will be understood that particular embodiments described herein
are shown by way of illustration and not as limitations of the invention.
The principal features of this invention can be employed in various
embodiments without departing from the scope of the invention. Those
skilled in the art will recognize, or be able to ascertain using no more
than routine experimentation, numerous equivalents to the specific
procedures described herein. Such equivalents are considered to be within
the scope of this invention and are covered by the claims.

[0107] All publications and patent applications mentioned in the
specification are indicative of the level of skill of those skilled in
the art to which this invention pertains. All publications and patent
applications are herein incorporated by reference to the same extent as
if each individual publication or patent application was specifically and
individually indicated to be incorporated by reference.

[0108] The use of the word "a" or "an" when used in conjunction with the
term "comprising" in the claims and/or the specification may mean "one,"
but it is also consistent with the meaning of "one or more," "at least
one," and "one or more than one." The use of the term "or" in the claims
is used to mean "and/or" unless explicitly indicated to refer to
alternatives only or the alternatives are mutually exclusive, although
the disclosure supports a definition that refers to only alternatives and
"and/or." Throughout this application, the term "about" is used to
indicate that a value includes the inherent variation of error for the
device, the method being employed to determine the value, or the
variation that exists among the study subjects.

[0109] As used in this specification and claim(s), the words "comprising"
(and any form of comprising, such as "comprise" and "comprises"),
"having" (and any form of having, such as "have" and "has"), "including"
(and any form of including, such as "includes" and "include") or
"containing" (and any form of containing, such as "contains" and
"contain") are inclusive or open-ended and do not exclude additional,
unrecited elements or method steps.

[0110] The term "or combinations thereof" as used herein refers to all
permutations and combinations of the listed items preceding the term. For
example, "A, B, C, or combinations thereof' is intended to include at
least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a
particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.
Continuing with this example, expressly included are combinations that
contain repeats of one or more item or term, such as BB, AAA, AB, BBC,
AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will
understand that typically there is no limit on the number of items or
terms in any combination, unless otherwise apparent from the context.

[0111] All of the compositions and/or methods disclosed and claimed herein
can be made and executed without undue experimentation in light of the
present disclosure. While the compositions and methods of this invention
have been described in terms of preferred embodiments, it will be
apparent to those of skill in the art that variations may be applied to
the compositions and/or methods and in the steps or in the sequence of
steps of the method described herein without departing from the concept,
spirit and scope of the invention. All such similar substitutes and
modifications apparent to those skilled in the art are deemed to be
within the spirit, scope and concept of the invention as defined by the
appended claims.

REFERENCES

[0112] U.S. Pat. No. 4,439,629: Extraction Process for Beta-Carotene.

[0113] U.S. Pat. No. 5,378,639: Solvent Extraction.

Patent applications by Board of Regents, The University of Texas System

Patent applications by Organic Fuels Algae Technologies, LLC

Patent applications in class Including cleaning or sterilizing of apparatus

Patent applications in all subclasses Including cleaning or sterilizing of apparatus